broken master: Some scenarios in ee/spec/models/push_rule_spec.rb are failing

Job #189399249 failed for f19e6226:

In this MR (https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10557), a lot of failing jobs were fixed by updating db/schema.rb. It doesn't fix all of the issues though as there are other failures in ee master like this one.

This job seems to be failing because PushRule#branch_name_allowed? seems to call an undefined method Gitlab::UntrustedRegexp#with_fallback.